Belief in the ability to teach or to teach a particular subject can help fuel success in the first stages of a teaching career. The need for a reliable instrument with which to probe preservice elementary teachers' self-efficacy beliefs in the teaching of science led to the development of two versions of a teacher efficacy scale that were tested in this study: the Teacher Efficacy Scale as modified by Kushner (1993), and the Science Teaching Efficacy Belief Instrument Form B (STEBI B) developed by Enochs and Riggs (1990). The two instruments were given to students in an elementary science methods course during the first 2 or 3 weeks of the semester. Typically students in this class were within a semester or two of student teaching. Both instruments were modifications of other instruments and the evolution of each is described. Both instruments used a Likert-type scale. The nature of this study suggested that a positive correlation might exist between the analogous scales of the two instruments. In both cases the correlation was negative. Preservice teachers with high personal efficacy tended to have lower science teaching efficacy, and those with high science teaching efficacy tended to have lower general teaching efficacy. Possible reasons for these results are discussed. (PVD)